1. Field of the Invention
The present invention relates to display devices, particularly to display devices with illumination light sources.
2. Description of the Related Art
The most widespread display technology is liquid crystal (LC) display technology. LC displays for mobile products need to operate over a very wide range of brightnesses and at as low power as possible.
If the displays are fully transmissive, then very powerful backlights are required for outdoor use. Thus, reflective and transflective displays have also been considered.
Reflective displays make use of the ambient illumination, and thus can not be seen in low light conditions. A solution for this is to add a top light which can be turned on in low ambient light conditions. However, it has not been possible previously to make a top light with good uniform illumination suitable for high performance displays. As a result, most displays on the market are transflective, making use of a backlight in low ambient light environments, and making use of the ambient light otherwise.
Such an arrangement gives a reasonably low power consumption, but image quality is very much compromised. Clearly, the most attractive option is a fully reflective display with a high quality top light whose brightness can be modified according to ambient light and image content.